Styrene-alkyd resin copolymer



' Patented Aug. 5, 1952 2,606,161" 'S'IYYBENE-ALKYD RES-IN ooremziilunr Paul E. Marling, Dayton, Ohio, as'signor to Mons santo Chemical Company, .St. Louis, Mo., a cor poration of Delaware No Drawing... ApplicaticnNovemberj251948;; v

, SB'riaLNO. 61,910.;

(on. see-2a) 12 "Claims.

This invention. relates to. improved coating,

of styrene hasbeen'dificult toaccomplish. The

incompatibility of polystyrene and drying oils causes low film strength, increases the susceptibility, of thefilm'towater and alkali, and induces the. formation. ofopaque. coatings. Although.

transparent copolym ers of. styrene and unsatu: rated alkyd,.resins have been prepared, the. re-

sulting films are, so1ub1e..in many commoner.

garlic-solvents, aretoothermoplastic for many applications, and. lack. durability under normal. These. copolymersl are weathering conditions. known. to. the. coatingv composition industry, as styrenated alkyd resins The. primary purpose. of a this invention, is. to

providea simple andreadily. reproduciblemethod.

of preparing j copolymers .of styrene and unsaturated alkyd'resi-ns. A iurther purpose of 'thisinvention is..-to.pr ovide copolymers of styrene. and.

alkyd resins. which. have unusual 1 solvent and thermal resistance,, and. excellent all-purpose utility.

Conventional unsaturated. alkyd resins are cross-linked linear polyesters; the" various. components of whic'lrxare unsaturated monocarboxq ylic"acid; polyhydric. alcohols; and polycarboxyli'c acids: The*'various'coniponents are so selected and proportioned so 'asto prepare high molecular' 'weight condensation. products with' a mini+ mum acid'number; In general, thecomponents are'so-selecte'd that there are approximately, the same-? number of available-hydroxylradicals and available-carboxyl radicals in the reaction mass: The'mo'lecular weight ofthe condensation products' may be determinedto'some' extent by the proportion of monofunc'ti'onal components, such as the unsaturated monocarboxylic acids, and the number of polyfunctional components, for example the polyhydri'c alcohols and the. polycarboxylic: acidsi. The" polyfunctiona'l components promote; the" long'chain molecules; Whereas the monofunctional componentsterminatethe polyester'chain's and therefore encourage. the formation of low" molecular: weight polymers;

In accordance with:this'invention it has been discovered thatiuhusuall y desirable. copolymers of styreneand/unsaturated alkyd resins are preparedfrcm alkyd resin-s. which have. incorporated substantial proportions or one. or more. aromatic. monocarboxylic acids Thearomaticacid enters.

the alkyd polymer reactionandevery molecule terminates.- a linear. polymer chain. By. varying the proportion of the. .aromatic monocarboxylic acid; adjustment. oi the molecular. weight ofthe alkyd.resin. is. possible, .butin all cases-it willbe lowercthan that'ofla. similar polymer made. with.-

out .the. monocarboxylic acid; Suitable aromatic.

monocarboxylic acids-arefbenzoic acid, and alkyl substituted.- benzoic acids, .wherein. from one to. threealkyl ..subs.tituents,l -each-. of T one tothree.

carbonatoms inlength' .maybe present, for ex-- ample .toluic' acid and .35.difnethyl benzoic acid.

Th alkyd.,resinshave as. their polymerizable radicals 'thosederived. from various drying .oils,

drated'cast'or oil, isomerized linseed oil, oiticia oil, and other'drying and semi-drying oils which are, triglyceridsof predominantly ethylenic u-nsaturated monocarbox-ylic. acids, such as oleic acid, l inolei ';1acid, ,linolenic acid,'.eleostearic acid,

and. geranic' acid. Theiaforementioned ethylenic unsaturated. monocarboxylic acids have from about 10f to. about 20 carbon atoms. The drying oil acids arecondensed with polyhydric alcoholshaving at least three hydroxyl'radicals and with dicarboxylic acids. Suitable polyhydroxy alcohols are glycerol, erythritol, pentaerythritol, sorbitol and. mannitoL. Suitable dicarboxylic acids are phthalic' acid; maleic. acid, succinic acid, fumaricacid, adipic acid, itaconic' acid, the anhydrid'es of various-cis-dicarboxylic acids and other polycarboxylic acids. In addition. to'the above described conventional alkydiresin' components' a substantial proportion of aromatic monocarboxylic acid is added thereto, for examplebenzoic'acid and 13011110 acid;

The proportions of the various; alkyd resin components which .are useful in the this invention may. be conveniently described with respect to the percentages of each acidic component based" upon. the equivalence to the p0lyhydric'alcol'iolpresent. Itis generally desired to have approximately the stoichiometric equivalent to the polyhydroxy alcohol oficarboxylicacid radicals .in' the alkyd'resin. In other Wordsit' is desired tohave approximately a zero acid number inth'e alkyd resin: As is wellknown in the art it is actually necessaryto charge an.

practice of alcohol.

excess of the polyhydric alcohol can be employed. The carboxylic acid groups present are calculated on the basis of the equivalent hydroxyl groups without including the excess polyhydric Thus, the aromatic monocarboxylic acid should be used in the amount of from 35 to 81 percent of the amount equivalent to the hydroxyl radical of the polyhydric alcohol. The dicarboxylic acid should be used in an amount of from 1 to 7 percent of the amount equivalent to the polyhydric alcohol. For best results the ethylenic unsaturated monocarboxylic acid should be between 12 and 60 percent or the amount equivalent to the polyhydroxy compound, and when mixed acids of this class are employed a substantial portion of the mixed acids must be drying oil acids which contain at least two ethylenic bonds. Accordingly, the term ethylenic unsaturated monocarboxylic drying oil acid is understood to include the monoethylenic monocarboxylic acids and minor amounts of saturated monocarboxylic acids present in natural drying and semi-drying oils. In the appended specification and claims these percentages are termed percent equivalent."

The unsaturated alkyd resins may be prepared by mixing the desired proportion 01' at least one of each of the above described components, ethylenic unsaturated monocarboxylic acid, polyhydroxy alcohol, dicarboxylic acid and aromatic monocarboxylic acid. The reactants are mixed and heated to a: temperature between 200 and 500 F. to efiect a condensation. This condensation is an esterification procedure and if desired conventional esterification catalysts, such as sulfuric acid and p-toluene sulfonic acid may be used. Conventional apparatus may be used, for example, retorts provided with water cooled reflux condensers adapted to remove the water from the condensate continuously throughout the reaction.

An alternative method of preparing the alkyd resins involves the use of drying oils which are heated with glycerol orother polyhydroxy alcohol in suitable proportions for converting the triglyceride to the monoglyceride, or the monoesters of the other polyhydroxy alcohol ii one is used. The mixture of esters so obtained will have a substantial excess of available hydroxyl radicals which must be reacted with additional carboxylic acids. Accordingly, th reaction is continued by the addition of dicarboxylic acids and monocarboxylic acid in selected proportions.

The unsaturated alkyd resins prepared in accordance with the preceding paragraphs are then copolymerized with styrene and with a-methyl substituted styrene, such as a-methyl styrene, isopropenylbiphenyl, and a-para-dimethyl styrene. The preferred composition comprises from about 25 to about 75 per cent of the unsaturated alkyd resin, from about 15 to about 50 per cent styrene, and from about to about 25 per cent of a compound from the class consisting of a-methylstyrene, isopropenylbiphenyl and a-pdimethylstyrene, all by weight per cent. The copolymerization is effected by mixing styrenes with a suitable polymerization catalyst and heating at a temperature between 200 and 500 F. for a periodof time suflicient to complete the copolymerization. Suitable catalysts for effecting this polymerization are the peroxides which are soluble in the reactants of the polymerizing mixture, such as benzoyl peroxide, acetyl peroxide, tetra-butyl hydroperoxide, isopropyl percarbonate, hydrogen peroxide, and other compounds containing a peroxy group, which are soluble in the polymerizing mass. The extent of polymerization may be estimated by viscosity measurements.

The solid or viscous liquid copolymer of styrene and/or other vinyl or isopropenyl aromatic hydrocarbon is dissolved in a suitable solvent and in such solution form used as a coating composition. Suitable solvents for dissolving the new styrenated alkyd resins are turpentine, mineral spirits, xylene, benzene, and other similar solvents. The coating composition may be comprised of from 10 to percent by weight of the solvent.

The coating compositions may in addition be compounded with other conventional paint and varnish components. If desired the coating compositions may be blended with drying oils, such as linseed oil, soy bean oil, and tung oil, synthetic resins, such as phenolic resins, and other resins both natural and synthetic, metallic driers, for example the various carboxylic acid salts of cobalt, lead and manganese, particularly the naphtenates, and pigments, for example white lead, iron oxide, lithopone and lead chromate. The film-forming compositions may be used on wood, metal, cloth, paper, leather, and may be applied by brushing, dipping, spraying, or other conventional technique.

Further details in the preparation and use of the new coating compositions are set forth with respect to the following specific examples.

Example 1 A suitable reaction flask was charged with 122 parts by weight of a mixture of percent benzoic acid and 5 percent phthalic anhydride, 50 parts of 98 percent glycerine' and 40 parts of the fatty acids of dehydrated V castor oil. While passing a stream or carbon dioxide throughthe vessel and with vigorous agitation by means of a propeller type stirrer, operating at a peripheral speed of 600 feet per minute, the reaction mass was heated for one hour at 460 F. The resulting product was a pale yellow, clear liquid having an acid number of twelve. Fifty parts by weight oi. the above described. resinous material was charged to a suitable flask and while heating at about 320 F., a mixture of 100 parts by weight of styrene, 40 parts of a-methyl styrene, and 5 parts of benzoyl peroxide were gradually added at a rate which required four hours for the com-' plete combination of reagents, during which time the mixed composition was held at thev reflux temperature of the system. Then the temperature was gradually raised to 480 F. in two hours and then the composition was allowed to cool. A liquid resinous composition so obtained was dissolved in an equal volume of xylene.

The product was used to coat metal panels and baked for five minutes at 300 F. A hard film was so produced which was less soluble in xylene and less thermoplastic than the control samples prepared in identical manner but without the use of benzoic acid.

Example 2 Using the procedure described in the preceding example 31 grams of 98 percent glycerine, 61

grams of the mixture of 95 percent benzoic acid and 5 percent phthalic anhydride, and 80 parts 5.1. allryd. resin soipreparedwas charged. ,toaireaction flask and a'mixtureof 'l00-gramsaofiTstyrene, 40 grams: oi a-meth-yl styrene and", grams of' benzoyl peroxide: was" added thereto dropwise.

overa period of fi vehours-at reflux temperature. 5

The; temperature was then raised gradually to 460 'F. over a-nine hour periodl Theresulting copolymerwas clean-nearly colorlessfland completely-soluble in xylene. The resin was dissolved inpetr oleum spirit -to forma usefulrcoating com.- position. Q q

Glass panels were then. coated Lwith' i the, res inous :solution and cured for fifteen mi'nutes-= at 300 71 The films so obtained lW-ere lle'ss soluble. in xyleneand less thermoplastic than-comparable films not containing. the benzoic acid,

The invention isdefined' bythe; following.

claims. v

1. A copolymer of il5lto. 50 percent'byjweiglitl. 20 styrene, ,from elo to 25 peroentof acompoundiof l theclass consisting of, a-meth yl stylene, iso-'.- propenylbiphenyl .and a-p-dimethyl styrene, and 25 110 75 percent of an unsaturated alkyd; resin of low acidnumber prepared by'the' condensaetion of a polyhydroxy alcohol havingiatleast three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of an ethylenic unsaturated monocarboxylic drying oil acid having from ten' to twenty'carbon atoms, from one toseven percent equivalent or a dicarboxylic acid, and from 35 to 81 percent equivalent of an aromaticxmonocarboxylic"acid of the type Ra wherein R-is' an alkyl radi'cal-having up to three carbonatoms and x is a smalliwhole number from zero to three, inclusive.

2. A liquid coating composition comprising a to 90 percent by weight solution in a volatile organic solvent of a copolymer of 15 to 50 percent by weight styrene, from 10 to percent of a compound of the class consisting of e-methyl styrene, isopropenylbiphenyl and a-p-dimethyl styrene, and 25 to 75 percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of an ethylenic unsaturated monocarboxylic drying oil acid having from ten to twenty carbon atoms, from one to seven percent equivalent of a dicarboxylic acid, and from to 81 percent equivalent of an aromatic monocarboxylic acid of the wherein R is an alkyl radical having up to three carbon atoms and a: is a small whole number from zero to three, inclusive. 65 3. A copolymer of 15 to 50 percent by weight styrene, from 10 to 25 percent of a compound of the class consisting O1 a-methyl styrene, isopropenylbiphenyl and a-p-dimethyl styrene, and 25 to '75 percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of an ethylenic unsaturated monocarboxylic drying oil acid acoa en having, fromctenitortwenty carbon atoms, from onei toLSeVenpercentiequivalentlofia.riiarboxylicV acid; and; from 35: 811' percent equivalent 1 of I benzoiciacidl 43 A li'quidicoatifig,composition;comprising;a, 10 itoi90cp erc'ent by weight solution of "a volatile organic solvent of la copol'ymer of J151 to I per-. 10ito 25"percentilo'f acompound! of Lth'e, classconsisting of L's-methyl. styrene, isopropenylblphenyl' and'aeppdimethyl' cent by weigh'tLstyrene, ,from

styrene; andl25itoy75cpercent or an Lunsaturated alkydflresin of low acid, numberiprepared. by, the condensation of =a polyhydroxy aleoholihaving'i at least three hyd-roxyl g roups ;and.- a mixture1con+. I

sisting, 01mm ..12"lt'o fidipercent'equivalent "or an ethylenicwunsaturatedgmonocarboxylic cryin oil. acidlhavingi from "ten ,'to, twenty-carbon atoms, from. ,one; to. seven gl cent equivalent; of I. a di= carboxylic acid, and fr'om 35 toi8l'rpercentiequi-vealent of benzoiciacidi l 5; -A' copol'ymer of p 15 t QSOIpercent by f weight styrene, -.from'illoltoi25percentofa compoundoff the classrconsisting. of. e-rnethyl styrene, 'isopropenylb'iphenyl .and -a ep-dimethyl styrene, and'l.

25 to 75?. percent of, an unsaturated .alkyd resin of low acid'number prepared by. the condensation of a polyhydroxy, alcohol havingjat-leastlthree hydroxyl groups andamixture consisting of from 121:0 percent equivalentfof dehydrated'ca'stor oil" acids, from one to sevenpercent equivalent 1 of a dicarboxylic acid, an'dfrorn' *35 to f81" percent equivalent of an aromatic monocarboxylic'acid carbon atoms-ands is i a small whole number from zero to three, inclusive; y

6. A liquid coating composition comprising a 10 to 90 percent by weight solution in a volatile organic solvent of a copolymer of 15 to 50 percent by weight styrene, from 10 to 25 percent of a compound of the class consisting of a-methyl styrene, isopropenylbiphenyl and c-p-dimethyl styrene, and 25 to percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of dehydrated castor oil acids, from one to seven percent equivalent of a dicarboxylic acid, and from 35 to 81 percent equivalent of an aromatic monocarboxylic acid of the type wherein R is an alkyl radical having up to three carbon atoms and a: is a small whole number from zero to three, inclusive.

7. A copolymer of 15 to 50 percent by weight styrene, from 10 to 25 percent of a compound of the class consisting Of a-methyl styrene, isopropenylbiphenyl, and a-p-dimethyl styrene, and 25 to '75 percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of dehydrated castor oil acids, from one to seven percent equivalent of phthalic acid, and from 35 to 81 percent equivalent of benzoic acid.

8. A liquid coating. composition comprising a i to 90 percent by'weight solution'in a volatile organic solvent of a copolymer of to 50 percent by weight styrenarrom 10 to 25 percent of a compound or'the 'class consisting ore-methyl styrene, isop'rop'enylbiphenyl and a -pj-dimethyl styrene, and 25 tc 75 percent of anunsaturated alkyd resin of low acid nuinber prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture con sisting of from 12 to; 6Qpercent' equivalent of dehydratedcasmr oil acids, from one to seven percent equivalent of phthalic acid, and from 35 to 81 percent, 1 equivalent of benzoic acid.

'9. A ,copolymer of 15 to'50percent by weight styrene, frorn'10 to 25 percent oia compoundof the class consisting of a-methyl styrene, isopro-' penylbiphenyl, and a-p-dimethyl styrene, and 25 to 75 percent of an unsaturated alkyd resinof low acid number prepared by the condensation of a polyhydroxy alcohol havlngat least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of linseed oil acids, from one to seven percent equivalent of phthalic acid, and from 35 to '81 percent equivalent of benzoicacid.

10. A liquid coating composition comprising a 10 to 90. percent by weight solution in a volatile organic solvent of a copolymer of 15 to 50 percent by weight styrene, from 10 to 25 percent of a compoundof the class consisting of a-methyl styrene, isopropenylbiphenyl and a-p-dimethyl styrene, and 25 to 75 percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12.to 60 percent equivalent of linseed oil acids. from one to' seven percent equivalent o1 phthalic acid, and from 35 to 81 percent.

equivalent of benzoic acid.

11. A copolymer of 15 to percent by weight styrene, from 10 to 25 percent of a compound of the class consisting of a-methyl styrene, isopropenylbiphenyl and a-p-dimethyl styrene, and 25 to 75 percent or an unsaturated alkyd resin 0! low acid number prepared by the condensation of a polyhydroxy alcohol having at leastthree hydroxyl groups and a mixture consisting of from 12 to percent equivalent or dehydrated castor oil acids, from one to seven percent equivalent or phthalic acid, and from 35 to 81 percent equivalent or toluic acid.

12. A liquid coating composition comprising a 10 to 90 percent by weight solution in a volatile organic solvent or a copolymer of 15 to 50 percent by weight styrene, from 10 to 25 percent of a compound of the class consisting of a-methyl styrene, isopropenylbiphenyl and a-p-dimethyl styrene, and 25 to percent of an unsaturated alkyd resin of low acid number prepared by the condensation of a polyhydroxy alcohol having at least three hydroxyl groups and a mixture consisting of from 12 to 60 percent equivalent of dehydrated castor oil acids, from one to seven percent equivalent of phthalic acid, and from 35 to 81 percent equivalent of toluic acid.

PAUL E. MARLING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED I STATES PATENTS Grless et a1. May 3, 1949 

1. A COPOLYMER OF 15 TO 50 PERCENT BY WEIGHT STYRENE, FROM 10 TO 25 PERCENT OF A COMPOUND OF THE CLASS CONSISTING OF A-METYL STYLENE, ISOPROPENYLBIPHENYL AND A-P-DIMETHYL STYRENE, AND 25 TO 75 PERCENT OF AN UNSATURATED ALKYD RESIN OF LOW ACID NUMBER PREPARED BY THE CONDENSATION OF A POLYHYDROXY ALCOHOL HAVING AT LEAST THREE HYDROXYL GROUPS AND A MIXTURE CONSISTING OF FROM 12 TO 60 PERCENT EQUIVALENT OF AN ETHYLENIC UNSATURATED MONOCARBOXYLIC DRYING OIL ACID HAVING FROM TEN TO TWENTY CARBON ATOMS, FROM ONE TO SEVEN PERCENT EQIVALENT OF A DICARBOXYLIC ACID, AND FROM 35 TO 81 PERCENT EQUIVALENT OF AN AROMATIC MONOCARBOXYLIC ACID OF THE TYPE 